NATIONAL STRATEGY FOR THE SURVIVAL OF RELEASED LINE-CAUGHT FISH: A REVIEW OF RESEARCH AND FISHERY INFORMATION FRDC Project 2001/101 McLeay, L.J, Jones, G.K. and Ward, T.M. November 2002 South Australian Research and Development Institute (SARDI) PO Box 120, Henley Beach, South Australia 5022 ISBN 0730852830 NATIONAL STRATEGY FOR THE SURVIVAL OF RELEASED LINE-CAUGHT FISH: A REVIEW OF RESEARCH AND FISHERY INFORMATION McLeay, L.J, Jones, G.K. and Ward, T.M. November 2002 Published by South Australian Research and Development Institute (Aquatic Sciences) © Fisheries Research and Development Corporation and SARDI. This work is copyright. Except as permitted under the Copyright Act 1968 (Cth), no part of this publication may be reproduced by any process, electronic or otherwise, without specific written permission of the copyright owners. Neither may information be stored electronically in any form whatsoever without such permission. 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ISBN No. 0730852830 TABLE OF CONTENTS LIST OF FIGURES .................................................................................................................................................6 LIST OF TABLES ...................................................................................................................................................7 ACKNOWLEDGMENTS ......................................................................................................................................8 NON-TECHNICAL SUMMARY ........................................................................................................................9 OUTCOMES ACHIEVED ................................................................................................................................. 11 GLOSSARY............................................................................................................................................................ 12 BACKGROUND.................................................................................................................................................... 13 NEED ........................................................................................................................................................................ 14 RATIONALE AND APPROACH.................................................................................................................... 14 OBJECTIVES ........................................................................................................................................................ 14 CHAPTER 1. REVIEW OF INFORMATION RELATING TO POST–RELEASE SURVIVAL OF LINE-CAUGHT FISH IN AUSTRALIAN FISHERIES. ................................................................... 15 1.1 INTRODUCTION.......................................................................................................15 1.2. WHY FISH ARE RELEASED: FACTORS AFFECTING RELEASE PATTERNS AND TOTAL NUMBERS RELEASED. ....................................................................................................16 1.2.1 Regulations ......................................................................................................17 1.2.2 Social (Voluntary release - fishers attitudes).......................................................19 1.2.3 Life-history phases and fish behaviour ...............................................................20 1.2.4 Incidental capture.............................................................................................21 1.3 SOURCES OF DATA FOR CATCH AND RELEASE IN AUSTRALIAN LINE FISHERIES ............22 1.3.1 Recreational surveys .........................................................................................22 1.3.2 Charter-boat/Land based tour data sources........................................................24 1.3.3 Commercial line catch information....................................................................24 1.3.4 Indigenous sector..............................................................................................25 1.4 EFFECTS OF CATCH AND RELEASE ON FISH ................................................................25 1.4.1 Stress...............................................................................................................25 1.4.2 Changes in reproductive potential......................................................................25 1.4.3 Changes in immune response.............................................................................26 1.4.4 Changes in behaviour .......................................................................................26 1.4.5 Growth.............................................................................................................27 1.4.6 Barotrauma effects............................................................................................27 1.4.7 Effects of deflation ............................................................................................28 1.4.8 Thermal shock ..................................................................................................29 1.4.9 Osmoregulatory stress.......................................................................................30 1.4.10 Oxygen deprivation and ammonia toxicity ........................................................30 1.4.11 Predation after release ....................................................................................31 3 1.5 FACTORS THAT INFLUENCE POST RELEASE SURVI VAL OF LINE-CAUGHT FISH ...............32 1.5.1 Fish vulnerability to multiple captures ...............................................................32 1.5.2 Size, age and gender effects on post-release injury and survivorship ....................32 1.5.3 Capacity of line fished populations to withstand catch-and-release mortality........34 1.5.4 Terminal gear type, hooking location and hook shedding.....................................34 1.5.4.a Hook composition (stainle ss steel v non) and shedding ................................. 35 1.5.4.b Hook shape and hooking location ................................................................ 35 1.5.4.c Barbed v barbless hooks.............................................................................. 36 1.5.4.d Size of hook and bait .................................................................................. 36 1.5.4.e Treble hook v single hook ........................................................................... 37 1.5.4.f Bait v lure .................................................................................................. 38 1.5.5 Capture duration/ Play length............................................................................38 1.5.6 Handling ..........................................................................................................39 1.6 HOW TO M EASURE THE EFFECTS OF CATCH AND RELEASE ON FISH ..............................40 1.6.1 Measuring stress responses ...............................................................................40 1.6.2 Experiments on captive fish. ..............................................................................41 1.6.3 Mark recapture/Tagging ...................................................................................42 1.6.4 Combining tagging and stress diagnostic measures.............................................44 1.6.5 Modelling.........................................................................................................44 1.7 HARM MINIMISATION PROCEDURES: PRECAUTIONARY MEASURES TO ENHANCE SURVIVAL ....................................................................................................................45 1.8 DISCUSSION ............................................................................................................46 CHAPTER 2: FUTURE RESEARCH PRIORITIES FOR ASSESSING POST-RELEASE SURVIVAL IN AUSTRALIAN LINE FISHERIES .................................................................................... 51 2.1 INTRODUCTION.......................................................................................................51 2.2 METHODS...............................................................................................................52 2.2.1 Commercial fisheries ........................................................................................52 2.2.2 Recreational fisheries........................................................................................52 2.2.3 Scientific information........................................................................................53 2.2.4 Prioritising species for research ........................................................................53 2.2.5. Confirming species for research........................................................................58 2.2.6 Prioritising research on factors affecting post-release survival............................59 2.3 RESULTS.................................................................................................................59